In several industrial fields, article manipulating machines, for instance packing machines, are used which comprise a feeding group consisting of a chain of conveyor belts, arranged one after the other, which receive the articles from a production station, suitably space them apart and supply them to a final belt provided with equally spaced, outward projecting transversal teeth, defining a continuous succession of recesses each intended to receive an article and to deliver it to the packing machine. Said final belt moves at a speed given by the packing machine, while the preceding belts and particularly the spacing belt(s) can be driven by their own motors. In any case, the speed of said spacing belt(s) is related to that of the final belt, in order that the articles are positioned on the spacing belt(s) so as to be properly received by said recesses.
As the operation of the production station is independent of that of the feeding group, the articles arrive at random instants on the spacing belt(s) so that the article position relative to the recesses may require adjustment: in effect, in order that the article manipulating machine operates properly, the articles must be located within the recesses in a well defined position, with rather narrow tolerance margins.